A piezoelectric sensor is, for example, mounted on a multifunction mobile terminal, and detects a press on a touch panel. A conventional piezoelectric sensor is, for example, a transparent piezoelectric sheet disclosed in Patent Literature 1. This transparent piezoelectric sheet includes a piezoelectric film, adhesive layers and plate electrodes. The plate electrodes are disposed on both principal surfaces of the piezoelectric film with the adhesive layers interposed therebetween. When this transparent piezoelectric sheet is pressed, a voltage corresponding to the press is produced in the piezoelectric film. By transmitting this voltage from the plate electrodes to a detection circuit, it is possible to detect a press.
PTL 1: Japanese Patent Application Laid Open No. 2011-222679